Abstract

We show that an advanced cathode buffer design, consisting of bathocuproine/3,4,9,10-perylenetetracarboxylic bis-benzimidazole/Ag, increases the short-circuit current of organic planar heterojunctioncells and reduces the J-V slope at reverse voltages. We study the physical origin of these effects by measuring reflectivity, voltage dependent external quantum efficiency, and voltage dependent photoluminescence. Our findings suggest that the observed effects are mainly associated with a voltage dependent polaron-induced exciton quenching in the C60 layer. Finally, this improved cathode buffer design is applied to a diindeno[1,2,3-cd:1′,2′,3′-lm]perylene/C70 based cell, leading to a considerable planar heterojunction efficiency of 5.7%.

Received 08 November 2012Accepted 14 January 2013Published online 29 January 2013

Acknowledgments:

The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement 287818 of the X10D project. Additionally, the authors wish to thank Erwin Vandenplas for processing support and sample preparation.

Abstract

We show that an advanced cathode buffer design, consisting of bathocuproine/3,4,9,10-perylenetetracarboxylic bis-benzimidazole/Ag, increases the short-circuit current of organic planar heterojunctioncells and reduces the J-V slope at reverse voltages. We study the physical origin of these effects by measuring reflectivity, voltage dependent external quantum efficiency, and voltage dependent photoluminescence. Our findings suggest that the observed effects are mainly associated with a voltage dependent polaron-induced exciton quenching in the C60 layer. Finally, this improved cathode buffer design is applied to a diindeno[1,2,3-cd:1′,2′,3′-lm]perylene/C70 based cell, leading to a considerable planar heterojunction efficiency of 5.7%.